Dale Earnhardt Jr. was frustrated after a crash at Talladega Superspeedway took out his No. 88 Chevrolet. / Kevin Liles, US Presswire

by Nate Ryan, USA TODAY Sports

by Nate Ryan, USA TODAY Sports

CONCORD, N.C. -- Dale Earnhardt Jr. will miss the next two Sprint Cup races at Charlotte Motor Speedway and Kansas Speedway with concussion symptoms following a last-lap crash Sunday at Talladega Superspeedway.

Earnhardt admitted during a news conference Thursday morning that he first suffered a concussion during an Aug. 29 tire test at Kansas that wasn't diagnosed until Wednesday.

Earnhardt said he was suffering headaches shortly after the 25-car pileup at Talladega. NASCAR's most popular driver seemed dazed after initially exiting his Impala on Sunday but said he was fine.

"The wreck at Kansas was really severe and it surprised me how tough it was to get past that," said Earnhardt, who said he would rest this weekend and would not attend Saturday's Bank of America 500.

"I remember everything about that accident and everything after that accident, but you know your body and how your mind works, and I knew something was just not quite right. I decided to just try to push through and work through it."

It's not the first or second concussion in NASCAR for Earnhardt, who sparked controversy in 2002 when he said he had raced with one for several races that season. NASCAR altered its policy on clearing drivers to return after crashes in the wake of the news.

Earnhardt said Thursday he had suffered other mild concussions in the past.

He wasn't required to visit the Talladega care center Sunday because he drove away from the wreck -- notably with five-time champion and Hendrick Motorsports teammate Jimmie Johnson, who also was involved in the wreck, straddling his door -- but noticed similar symptoms that he experienced after the Kansas crash.

"I thought I was in the clear, but just that little accident at Talladega, I started having headaches and stuff immediately after the wreck, and then into the next day and into Tuesday, and I thought, man, this is pretty soon after the other accident in Kansas," Earnhardt said. "I should probably take this really seriously and seek some professional opinions on this."

NASCAR said it would let its doctor, Jerry Petty, determine if and when Earnhardt would be cleared for a return to the racetrack. Petty said Thursday that Earnhardt's neurological exam was normal but that the driver was pulled from competing because of his self-described symptoms.

"What we'll do now is we want him to have four or five days after he has no headache, and then we'll give him some sort of test like to get his pulse rate up, see if we can provoke a headache," Petty said. And then if we can't, we'll let him go out and drive a lap or two and see how that goes. And if that goes well, we'll probably clear him to race."

Team owner Rick Hendrick described removing Earnhardt from the No. 88 as "preventative maintenance," and the driver said Thursday he expected to return to resume his NASCAR career.

NASCAR senior vice president Steve O'Donnell defended the sport's concussion-screening standards and said there had been only nine reported concussions in the last five years in NASCAR's three national series.

Of course, there is no way to measure unreported concussions without a driver admitting it as Earnhardt did this week.

"It takes a lot of guts for an athlete of his caliber, where he stands in the sport, where he stood in the Chase to come up here and admit he had an issue," O'Donnell said. "It's everyone's responsibility in this sport to participate in the safety of all of our athletes.

"We know it's a dangerous sport," he added. "But we've got to be relying on our drivers, too, to be up front with us."

It''s been and up down season for Earnhardt, who made the Chase for the Sprint Cup for the second consecutive season and ended a four-year winless streak in June at Michigan International Speedway. Since the Chase began, he hasn't finished in the top five in four races.

On Thursday, Earnhardt said he was feeling "80-90%" entering the Chase and felt 100% entering Talladega.

After Sunday's race, Earnhardt assailed the racing at Talladega as "bloodthirsty" and said he would "find another job" if NASCAR had the style of restrictor-plate racing found there and at Daytona International Speedway every week. He backtracked on those statements Tuesday in an interview with SB Nation.

The development effectively ends his bid for a first Cup championship after he spent part of the 26-race regular season in the points lead. Earnhardt is in 11th place, 51 points behind leader Brad Keselowski with six races to go in the season. He is now almost guaranteed to finish last in the Chase.

Johnson lauded Earnhardt's coming forward but said ending a streak of 461 consecutive starts, fifth-longest among active Cup drivers, would be tough on his teammate. This will mark the first race since Sept. 3, 1979, that an Earnhardt won't be in a Cup-race starting grid. (Earnhardt's father, Dale Earnhardt Sr., was a seven-time champion that was killed in the 2001 Daytona 500.)

"I credit Junior for being aware of how he feels, what's going on. It's going to be a tough week for him," Johnson said. "I don't think the significance of missing the race has set in yet, still going through his workload and his business, but it's going to be tough."